1 files changed, 141 insertions, 0 deletions

diff --git a/Rx.NET/System.Reactive.Linq/Reactive/Linq/Observαble/TakeLastBuffer.cs b/Rx.NET/System.Reactive.Linq/Reactive/Linq/Observαble/TakeLastBuffer.cs
new file mode 100644
index 0000000..71b36b0
--- /dev/null
+++ b/Rx.NET/System.Reactive.Linq/Reactive/Linq/Observαble/TakeLastBuffer.cs
@@ -0,0 +1,141 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved. See License.txt in the project root for license information.
+
+#if !NO_PERF
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Reactive.Concurrency;
+using System.Reactive.Disposables;
+
+namespace System.Reactive.Linq.Observαble
+{
+    class TakeLastBuffer<TSource> : Producer<IList<TSource>>
+    {
+        private readonly IObservable<TSource> _source;
+        private readonly int _count;
+        private readonly TimeSpan _duration;
+        private readonly IScheduler _scheduler;
+
+        public TakeLastBuffer(IObservable<TSource> source, int count)
+        {
+            _source = source;
+            _count = count;
+        }
+
+        public TakeLastBuffer(IObservable<TSource> source, TimeSpan duration, IScheduler scheduler)
+        {
+            _source = source;
+            _duration = duration;
+            _scheduler = scheduler;
+        }
+
+        protected override IDisposable Run(IObserver<IList<TSource>> observer, IDisposable cancel, Action<IDisposable> setSink)
+        {
+            if (_scheduler == null)
+            {
+                var sink = new _(this, observer, cancel);
+                setSink(sink);
+                return _source.SubscribeSafe(sink);
+            }
+            else
+            {
+                var sink = new τ(this, observer, cancel);
+                setSink(sink);
+                return sink.Run();
+            }
+        }
+
+        class _ : Sink<IList<TSource>>, IObserver<TSource>
+        {
+            private readonly TakeLastBuffer<TSource> _parent;
+            private Queue<TSource> _queue;
+
+            public _(TakeLastBuffer<TSource> parent, IObserver<IList<TSource>> observer, IDisposable cancel)
+                : base(observer, cancel)
+            {
+                _parent = parent;
+                _queue = new Queue<TSource>();
+            }
+
+            public void OnNext(TSource value)
+            {
+                _queue.Enqueue(value);
+                if (_queue.Count > _parent._count)
+                    _queue.Dequeue();
+            }
+
+            public void OnError(Exception error)
+            {
+                base._observer.OnError(error);
+                base.Dispose();
+            }
+
+            public void OnCompleted()
+            {
+                var res = new List<TSource>(_queue.Count);
+                while (_queue.Count > 0)
+                    res.Add(_queue.Dequeue());
+
+                base._observer.OnNext(res);
+                base._observer.OnCompleted();
+                base.Dispose();
+            }
+        }
+
+        class τ : Sink<IList<TSource>>, IObserver<TSource>
+        {
+            private readonly TakeLastBuffer<TSource> _parent;
+            private Queue<System.Reactive.TimeInterval<TSource>> _queue;
+
+            public τ(TakeLastBuffer<TSource> parent, IObserver<IList<TSource>> observer, IDisposable cancel)
+                : base(observer, cancel)
+            {
+                _parent = parent;
+                _queue = new Queue<System.Reactive.TimeInterval<TSource>>();
+            }
+
+            private IStopwatch _watch;
+
+            public IDisposable Run()
+            {
+                _watch = _parent._scheduler.StartStopwatch();
+
+                return _parent._source.SubscribeSafe(this);
+            }
+
+            public void OnNext(TSource value)
+            {
+                var now = _watch.Elapsed;
+                _queue.Enqueue(new System.Reactive.TimeInterval<TSource>(value, now));
+                Trim(now);
+            }
+
+            public void OnError(Exception error)
+            {
+                base._observer.OnError(error);
+                base.Dispose();
+            }
+
+            public void OnCompleted()
+            {
+                var now = _watch.Elapsed;
+                Trim(now);
+
+                var res = new List<TSource>(_queue.Count);
+                while (_queue.Count > 0)
+                    res.Add(_queue.Dequeue().Value);
+
+                base._observer.OnNext(res);
+                base._observer.OnCompleted();
+                base.Dispose();
+            }
+
+            private void Trim(TimeSpan now)
+            {
+                while (_queue.Count > 0 && now - _queue.Peek().Interval >= _parent._duration)
+                    _queue.Dequeue();
+            }
+        }
+    }
+}
+#endif
\ No newline at end of file